The present invention relates to a device for viewing the fundus of the eye, in particular by an optical system, for example a microscope, a slit lamp or an indirect ophthalmoscope, wherein the device is equipped with a handle and a lens system fastened to the handle, the lens system has a first lens with a concave lens surface, which can be placed onto the corona of an eye and can be combined with further lenses.
Such a device is known, for example, from German Gebrauchsmuster 298 19 341.8. The device is placed onto the eye for viewing the fundus of the eye. It is then possible to view the fundus of the eye with an optical system, for example, a microscope, a slip lamp or an indirect ophthalmoscope. An image of the retina or of the inside of the eye is created at a distance in front of the eye through the action of the first lens, to which image the microscope or another optical system is adjusted.
However, it is necessary during an eye examination or during eye surgery for the physician to alternately view the fundus of the eye and the foreground of the eye. To change the view, the device is either placed onto the eye or is removed from the beam path between the eye and microscope. However, since the microscope is either adjusted to the image of the fundus of the eye, which is created in front of the device, or is adjusted to the foreground of the eye, it is necessary when changing from the one view to the other view of the eye to refocus the microscope or the other optical system. This means in each case a loss of time of a few seconds, which unnecessarily extends the examinations or surgeries. Physicians therefore desire devices with which a change between viewing the fundus of the eye and the foreground of the eye can take place quickly and easily.
The basic purpose of the invention it therefore to provide a device with which the fundus of the eye can be viewed and which quickly changes for viewing of the foreground of the eye when the device is removed from the beam path between the eye and optical system.
This purpose is attained according to the invention in such a manner that a handle is provided with a mounting for a supplementary lens, which is moved in a viewing direction in front of the lens system, whereby the strength of the supplementary lens is chosen in such a manner that when viewing the fundus of the eye with the device, the optical system is clearly focused onto the foreground of the eye.
The supplementary lens inserted between the lens system and the optical system shifts the image of the fundus of the eye, namely of the retina or the inside of the eye, into a plane, which lies in the area of the foreground of the eye. Thus the microscope or the optical system must be sharply focused onto this plane in order to view the fundus of the eye. When the device with the lens system and the supplementary lens is now removed from the beam path between the eye and the optical system, then the optical system remains focused on the plane in the area of the foreground of the eye so that this area can be viewed directly by the optical system. Thus complicated refocussing of the optical system is removed.
The supplementary lens according to the invention can be a collective lens or collecting lens system, which can be exchangeably held in a mounting. The distance between the supplementary lens and the lens system can be changed according to the present invention.
The device has, in a specific design of the invention, an illuminating device, the outlet surface of which lies within the first lens of the lens system or ends flush with a lens surface of the first lens.
The lens system is advantageously enclosed in a housing, whereby according to the invention the entire device can be sterilized and/or autoclaved.